I think it's very important to have a good explanation of what Bitcoin is and how it works on bitcoin.org, translated into many languages. Bitcoin is still something very new and different and most people don't know much about it. While the wiki is nice for in-depth articles a short but correct overview (say 2..3 subpages: What it is, how to use it and fundamental protocol rules) will be helpful to users just discovering bitcoin. It shouldn't go too much into how it is used today, though. Just explain what you can do with it (i.e. no RPC documentation) and don't focus too much on the "official" client.